1. Field of the Invention
The invention relates to an output buffer, and more particularly to an output buffer applied in a source driver.
2. Description of the Related Art
FIG. 1 is a schematic diagram of a conventional output buffer. The output buffer 100 comprises input stage circuits 111 and 113, output stage circuits 131 and 133, and an output multiplex unit 150. The output buffer 100 increases the driving capability of the input signals IN1 and IN2 to successfully drive the load units L1 and L2. However, the transistor sizes of the output stage circuit 131 and 133 and the output multiplex unit 150 are increased as a result. Thus, the size of the output buffer is increased.
In addition, when the output signals of the output stage circuit 131 and 133 approach a target, the voltage difference between the drain and the source of the transistor of the output multiplex unit 150 approaches 0V. If the load units L1 and L2 become heavier, when the output signals of the output stage circuits 131 and 133 approach the target, the driving speed of the output is reduced.